#include<iostream>
using namespace std;
int main()
{
	int n, t;cin >> n >> t;
	if (n == 1 && t == 10) cout << "-1" << endl;
	else if (t == 10)
	{
		cout << 1;
		for (int i = 1; i <= n - 1; i++)
		{
			cout << 0;
		}
	}
	else
	{
		for (int i = 1; i <= n; i++)
		{
			cout << t;
		}
	}
	return 0;
}